Radiopharmaceutical therapy (RPT) is an emerging cancer treatment that delivers radiation directly to cancer cells. The recent FDA approval of 223Ra(Xofigotm) for resistant metastatic prostate cancer and its commercial success provides an example of the therapeutic and commercial potential of this modality. In addition, drug companies have large libraries of targets and targeting molecules. Progress in chelators and commercial availability of therapeutic radionuclides such as Lu-177, and alpha emitters such as Pb-212 all are indicators that RPT is poised to become an important tool for cancer therapy. The RPT market, according to a BCC Research Report, is expected to increase annually by 10.4% between 2014 and 2019 to a total value of just over $1 billion, providing increased opportunities for dosimetry services. Clinicaltrials.gov lists more than 100 trials investigating this modality; more than 20 pharmaceutical companies are working in RPT, including Roche/Genetech, and Bayer/Algeta. FDA approval of RPT agents requires tumor and normal tissue dose estimates. European regulations mandate personalized dosimetry. Optimal use of RPTs is likely to require a precision medicine approach based on quantitative imaging and dosimetry. The founders of this company, Radiopharmaceutical Imaging and Dosimetry, LLC (RAPID) have IP developed over a combined 40+ years of NIH R01 grant support in quantitative imaging of radionuclides used in RPT, including challenging radionuclides like Y-90 (a beta emitter), Ra-223 and I-131, and 3D dosimetry and radiobiological modeling methods to predict response to cancer therapy. There are no commercial software tools or service providers and very limited expertise to perform these calculations. As a result, several companies have contracted with our labs to perform these calculations. However, the current software implementing the IP is not efficient enough to support a commercial service. To provide such a service it is necessary to develop a comprehensive quantitative imaging and dosimetry software tool chain with a browser-based GUI, that is user friendly and runs the computationally intensive activities on commodity cloud-based compute servers. To demonstrate the feasibility of developing such a tool we propose to (1) develop a browser-based GUI for image registration and segmentation of multi-modality images acquired at multiple time points; (2) design and implement a server-side framework for authentication and granting privileges to the browser-based GUI in (1); (3) design and develop an integrated quantitative imaging and dosimetry tool chain using a conventional GUI; and (4) test and validate the tools developed in aims (1)-(3) on a large anonymized database of Lu-177 peptide therapy patient datasets. Accomplishing these aims would demonstrate the feasibility and provide the basis for development and validation of a collaborative web-based quantitative imaging and dosimetry system for RPT in a Phase II project.